U.S. patent number 6,595,980 [Application Number 09/792,600] was granted by the patent office on 2003-07-22 for devices and methods for preventing distal embolization using flow reversal by occlusion of the brachiocephalic artery.
This patent grant is currently assigned to CoAxia, Inc.. Invention is credited to Denise R. Barbut.
United States Patent |
6,595,980 |
Barbut |
July 22, 2003 |
Devices and methods for preventing distal embolization using flow
reversal by occlusion of the brachiocephalic artery
Abstract
The invention provides a medical device having a catheter and
one or more expandable constricting/occluding members. The catheter
is adapted for use with therapeutic or diagnostic devices,
including an angioplasty/stent catheter and an atherectomy
catheter. The constrictor/occluder is mounted at the distal end of
the catheter. Manometers may be mounted distal to one or more
constrictors for measuring pressure distal to the constrictor(s).
Methods of using the devices for preventing distal embolization
during extra cranial or intracranial carotid procedures or
vertebral artery procedures by reversing blood flow in an internal
carotid artery, an external carotid artery, and/or a common carotid
artery toward the subclavian artery are disclosed.
Inventors: |
Barbut; Denise R. (New York,
NY) |
Assignee: |
CoAxia, Inc. (Maple Grove,
MN)
|
Family
ID: |
25157450 |
Appl.
No.: |
09/792,600 |
Filed: |
February 23, 2001 |
Current U.S.
Class: |
604/509;
604/96.01 |
Current CPC
Class: |
A61B
17/12031 (20130101); A61B 17/12036 (20130101); A61B
17/12109 (20130101); A61B 17/12136 (20130101); A61M
25/1011 (20130101); A61B 2017/00243 (20130101); A61B
2017/22067 (20130101); A61M 25/104 (20130101); A61M
2025/1015 (20130101); A61M 2025/1052 (20130101) |
Current International
Class: |
A61M
25/10 (20060101); A61B 17/12 (20060101); A61B
17/22 (20060101); A61B 17/00 (20060101); A61M
29/02 (20060101); A61M 031/00 (); A61M
029/00 () |
Field of
Search: |
;604/96.01,101.01,101.02,101.05,500,508,509 ;606/108,191,192,194
;623/1.11 |
References Cited
[Referenced By]
U.S. Patent Documents
Other References
Theron et al., "New Triple Coaxial Catheter System for Carotid
Angioplasty with Cerebral Protection," American Journal of
Radiology, 11:869-874, Sep./Oct. 1990..
|
Primary Examiner: Look; Edward K.
Assistant Examiner: Fristoe, Jr.; John K
Attorney, Agent or Firm: O'Melveny & Myers LLP
Claims
What is claimed is:
1. A method for treating a carotid artery occlusion, comprising the
steps of: inserting a distal end of a catheter into the right
brachiocephalic trunk, the catheter having a proximal end, the
distal end of the catheter having a constricting member; locating
the constricting member in the right brachiocephalic trunk upstream
of a carotid artery having an occlusion; expanding the constricting
member to constrict the right brachiocephalic trunk, wherein blood
flow in the carotid artery is reversed to pass over the occlusion
and toward the brachiocephalic trunk; and advancing a therapeutic
instrument into the carotid artery to reduce the occlusion.
2. The method of claim 1, Wherein the carotid artery having the
occlusion is the internal carotid artery.
3. The method of claim 1, wherein the carotid artery having the
occlusion is the common carotid artery.
4. The method of claim 1, wherein the carotid artery having the
occlusion is the external carotid artery.
5. The method of claim 1, further comprising the step of locating
an occluding member in the right vertebral artery to block
embolization to the right vertebral artery.
6. The method of claim 1, wherein the distal end of the catheter is
inserted into the subclavian artery in an antegrade direction.
7. The method of claim 1, wherein the occlusion partially occludes
the brachiocephalic artery.
8. The method of claim 1, wherein the occlusion is a stenosis.
9. The method of claim 1, wherein the occlusion is an embolus.
10. The method of claim 1, wherein the occlusion is an
atheroma.
11. The method of claim 1, wherein the constricting member is
expanded to occlude the brachiocephalic artery.
12. The method of claim 1, wherein the constricting member is a
balloon that communicates with an inflation lumen that extends to
the proximal end of the catheter.
13. The method of claim 12, wherein the balloon is a toroidal
balloon.
14. The method of claim 1, wherein the therapeutic instrument is an
angioplasty catheter.
15. The method of claim 1, wherein the therapeutic instrument is a
stent.
16. The method of claim 1, wherein the therapeutic instrument is an
atherectomy catheter.
17. The method of claim 1, wherein the catheter has a lumen adapted
to pass the therapeutic instrument.
18. The method of claim 17, wherein the catheter has a side opening
that communicates with the lumen and is adapted to pass the
therapeutic instrument.
19. The method of claim 1, further comprising the step of locating
a second constricting member in the right subclavian artery
downstream the takeoff of the right vertebral artery.
20. The method of claim 1, further comprising the step of locating
a second constricting member in the right subclavian artery
downstream the takeoff of the right common carotid artery and
upstream the takeoff of the right vertebral artery.
21. The method of claim 20, further comprising the step of
expanding the second constricting member to partially occlude the
subclavian artery.
22. The method of claim 1, further comprising the step of infusing
angiographic dye to confirm the reversal of blood flow.
23. The method of claim 1, wherein the distal end of the catheter
further comprises a radiopaque marker.
24. The method of claim 1, wherein a manometer is mounted distal
the constricting member.
Description
FIELD OF THE INVENTION
The present invention relates generally to devices and methods
useful in treating patients with stroke or occlusive
cerebrovascular disease. More specifically, the invention provides
an extracranial device capable of reversing flow down a vertebral
artery, an internal carotid artery, an external carotid artery
and/or a common carotid artery, and into the subclavian artery
during an invasive procedure, thereby avoiding distal embolization
of vascular debris. Various diagnostic or therapeutic instruments,
including an atherectomy catheter, a filter, and/or an
angioplasty/stent catheter, can be introduced through the device
for treating the occlusion. The invention may also be useful to
reverse flow and pull back embolic debris during a stroke.
BACKGROUND OF THE INVENTION
Stroke is the third most common cause of death in the United States
and the most disabling neurologic disorder. Approximately 700,000
patients suffer from stroke annually. Stroke is a syndrome
characterized by the acute onset of a neurological deficit that
persists for at least 24 hours, reflecting focal involvement of the
central nervous system, and is the result of a disturbance of the
cerebral circulation. When a patient presents neurological symptoms
and signs that resolve completely within 1 hour, the term transient
ischemic attack (TIA) is used. Etiologically, TIA and stroke share
the same pathophysiologic mechanisms and thus represent a continuum
based on persistence of symptoms and extent of ischemic insult.
Outcome following stroke is influenced by a number of factors, the
most important being the nature and severity of the resulting
neurologic deficit. Overall, less than 80% of patients with stroke
survive for at least 1 month, and approximately 35% have been cited
for the 10-year survival rates. Of patients who survive the acute
period, up to 75% regain independent function, while approximately
15% require institutional care.
Hemorrhagic stroke accounts for 20% of the annual stroke
population. Hemorrhagic stroke often occurs due to rupture of an
aneurysm or arteriovenous malformation bleeding into the brain
tissue, resulting in cerebral infarction. The remaining 80% of the
stroke population are hemispheric ischemic strokes and are caused
by occluded vessels that deprive the brain of oxygen-carrying
blood. Ischemic strokes are often caused by emboli or pieces of
thrombotic tissue that have dislodged from other body sites or from
the cerebral vessels themselves to occlude in the narrow cerebral
arteries more distally. The extracranial or intracranial internal
carotid artery, commonly affected by atherosclerosis causing
symptomatic occlusion in the arterial lumen, is often responsible
for hemispheric ischemic stroke and generating thromboembolic
material downstream to the distal cerebral vessels. Treatment of
the occluded carotid artery in patients with stroke and TIA or for
stroke prevention in patients with asymptomatic flow limiting
carotid stenosis includes performing angioplasty, stent placement,
or atherectomy on the occluded carotid artery. This is also true of
the vertebral artery. Unfortunately, placing instrumentation within
a diseased artery is associated with increased risk of ischemic
stroke, since manipulation of an atheromatous plaque in the
arterial wall often causes emboli to dislodge distally in the
narrow cerebral arteries.
Current methods of preventing distal embolization from carotid
instrumentation include insertion of a blood filter distal to the
occlusion and suctioning embolic debris during the procedures.
Disadvantages associated with the conventional methods are that (1)
inserting the filter through the atheromatous lesion is associated
with increased risk of distal embolization, (2) using suction to
reverse the flow in the internal carotid artery may increase a
patient's blood loss if the suctioned blood is discarded, and (3)
systemic anticoagulation and pumping may be required to recycle the
suctioned blood back into the arterial or venous system, and such
anticoagulation is associated with increased risk of
hemorrhage.
New devices and methods are thus needed for patients undergoing
carotid procedures for definitive or prophylactic treatment of
carotid plaque, which minimize the risk of distal embolization and
prevent ischemic stroke.
SUMMARY OF THE INVENTION
The invention provides devices and methods for preventing ischemic
stroke in patients undergoing percutaneous invasive vertebral or
carotid procedures, including angioplasty, stent placement, and/or
filter insertion, by reversing blood flow down a vertebral artery,
an extracranial or intracranial internal carotid artery, an
external carotid artery, and/or a common carotid artery and into
the ipsilateral subclavian artery. In this way, embolic debris
generated as a result of placing instrumentation within a diseased
artery is diverted to the subclavian artery, thereby preventing
stroke by minimizing distal embolization to the narrow cerebral
vessels. The devices and methods are also useful to remove an
embolus and improve flow (by reversing collateral blood flow across
the circle of Willis) in patients with acute stroke.
The invention utilizes devices comprising a catheter having one or
two expandable constricting members at its distal end. Each
constrictor may be a balloon, in certain cases a toroidal balloon,
or a device of any other appropriate shape, so that it can fully or
partially occlude blood flow. The lumen of the catheter may be
adapted for insertion of a therapeutic instrument, such as an
angioplasty, atherectomy, and/or stent catheter. A manometer is
optionally mounted proximal and/or distal to the constricting
member for monitoring blood pressure proximal and/or distal the
constrictor.
The occluder/constrictor is mounted near the distal. end of the
catheter, in certain cases proximal to a port. Each balloon
occluder and constrictor communicates with an inflation lumen and
an inflation port at the proximal end of the catheter. In certain
embodiments, the catheter will include first and second
constriction/occlusion members. The second constrictor is mounted
on a second member that is slideably insertable through the
catheter, and passes beyond the first constrictor. In this way, the
second member and the second constrictor are moveable
longitudinally relative to the first constrictor. In other
embodiments, the constrictor may consist of a balloon having more
than one opening at its center for the passage of blood, or may
consist of more than one expandable balloons allowing passage of
blood through the gap between the arterial wall and the expanded
balloons. The proximal end of the catheter may include a hemostatic
valve.
In still another embodiment, the catheter includes a second lumen
communicating with a proximal end and an infusion port at its
distal end. The port is located distal to the distal port of the
catheter. The second lumen and its port are adapted for delivering
a pharmaceutical agent to the carotid, brachiocephalic and/or
subclavian arteries, including an angiographic dye. Any device
described in Barbut, U.S. Pat. No. 6,146,370, incorporated herein
by reference in its entirety, may also be used in the methods
described herein.
The invention provides methods for reversing flow in a vertebral or
carotid artery having an atheromatous lesion. More specifically,
the methods are useful in reversing flow down a vertebral artery,
an extracranial or intracranial internal carotid artery, an
external carotid artery, and/or a common carotid artery and into
the subclavian artery. In a first method, using the devices
described above, the distal end of the catheter is inserted into
the right brachiocephalic artery. The catheter can be inserted over
a guidewire through an incision on a peripheral artery, including
the femoral artery, the subclavian artery, or the brachiocephalic
artery. The catheter is positioned to locate the constricting
member within the right brachiocephalic artery. Preferably, the
constrictor is expanded to completely or partially occlude the
right brachiocephalic artery. At a critically low brachiocephalic
pressure distal to the constriction, blood flow in the carotid and
vertebral arteries is reversed to pass over the atheromatous lesion
and into the right subclavian artery. The flow reversal can be
verified fluoroscopically with dye. If flow reversal fails to occur
or if augmentation of flow reversal is desired, a second
constricting member is expanded in the right subclavian artery,
further reducing the pressure in the subclavian artery to
facilitate reversal of flow down the carotid artery and into the
subclavian artery.
In another method, the distal end of the catheter is inserted into
the aorta in the takeoff of the left common carotid artery and left
subclavian artery. The catheter is positioned to locate the
constricting member within the inlet of the left subclavian artery
and the left common carotid artery. The constrictor is expanded to
completely or partially occlude the subclavian and common carotid
artery. At a critically low pressure, blood flow in the carotid
artery is reversed to pass over the atheromatous lesion and into
the left subclavian artery. The flow reversal can be verified
fluoroscopically with dye. If flow reversal fails to occur or if
augmentation of flow reversal is desired, a second constricting
member is expanded in the left subclavian artery, further reducing
the pressure in the subclavian artery to facilitate reversal of
flow down the carotid artery and into the subclavian artery.
In another method, using the device having a second occluder
including a shunt for the passage of blood therethrough, the
catheter is inserted in the right brachiocephalic artery, with the
first occluder located in the right brachiocephalic artery and the
second occluder located in the right subclavian artery. Preferably,
the first occluder is expanded to occlude the brachiocephalic
artery followed by expansion of the second occluder to occlude the
subclavian artery. Alternatively, the second occluder is expanded
to occlude the subclavian artery followed by expansion of the first
occluder to occlude the brachiocephalic artery.
After blood reversal is confirmed, procedures on either the
vertebral artery, the internal carotid artery or branches thereof
(e.g., MCA or ACA), external carotid artery, or common carotid
artery can be performed by advancing a therapeutic or diagnostic
instrument through the lumen and port of the catheter distal to the
occluder. An atherectomy catheter, for example, can be introduced
to remove the atheroma in the right internal carotid artery without
fear of distal embolization.
It will be understood that there are several advantages in using
the devices and methods disclosed herein for prevention of distal
embolization during use of instrumentation in the carotid arteries.
For example, the devices (1) abolish the need for suction distal to
the constricting/occluding member, thereby minimizing blood loss,
(2) eliminate the need for systemic anticoagulation, pumping, and a
second arterial or venous stick, all of which are required where
suction is employed, (3) can be used to introduce a variety of
diagnostic or therapeutic instrument to the carotid artery, (4) can
be used in any procedures which require instrumentation within the
carotid artery, (5) can be used for definitive treatment of acute
or subacute ischemic stroke, (6) can be used in the angiogram or
fluoroscopy suite available in most hospitals, (7) require only one
incision site for entry, and (8) can be used to perform an
interventional procedure without distal protection (e.g., a distal
filter), and without crossing the lesion.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 depicts normal cerebral circulation in the Circle of
Willis.
FIG. 2 depicts a reversed circulation in the Circle of Willis to
compensate for an occlusion in the left internal carotid
artery.
FIG. 3A depicts a distal region of an embodiment of the medical
device having an occluding member for prevention of acute stroke
during use of instrumentation in a carotid artery.
FIG. 3B depicts a distal region of another embodiment of the
medical device having a constricting member.
FIG. 4A depicts a distal region of another embodiment of the
medical device having a constricting member distal an occluding
member.
FIG. 4B depicts a distal region of another embodiment of the device
having two manometers.
FIG. 5 depicts the device of FIG. 4B including a hemostatic valve
at its proximal end.
FIG. 5A depicts another embodiment of the device having a proximal
occluder and a distal constrictor.
FIG. 5B depicts another embodiment of the device having a proximal
constrictor and a distal constrictor.
FIG. 5C depicts another embodiment of the device having a proximal
occluder and a distal occluder.
FIG. 5D depicts another embodiment of the device having a proximal
occluder and a distal occluder.
FIG. 6A depicts the device of FIG. 3A inserted in the right
brachiocephalic artery.
FIG. 6B depicts the expanded occluder causing reversal of blood
flow from the internal carotid artery to the subclavian artery.
FIG. 6C depicts an angioplasty balloon catheter inserted through
the device in FIG. 6B to treat an occluding lesion in the right
internal carotid artery.
FIG. 6D depicts the use of an occluder to establish carotid flow
reversal and a second balloon to protect the vertebral artery
against embolization.
FIG. 7A depicts the device of FIG. 3B inserted in the right
brachiocephalic artery.
FIG. 7B depicts the expanded constricting member causing reversal
of blood flow from the common carotid artery to the subclavian
artery.
FIG. 7C depicts an atherectommy catheter inserted through the
device in FIG. 7B to treat an occluding lesion in the right common
carotid artery.
FIG. 8 depicts the device of FIG. 5 inserted in the right
brachiocephalic artery and the right subclavian artery to increase
the pressure gradient between the right common carotid artery and
the right subclavian artery.
FIG. 9 depicts the constricting member of the device of FIG. 3B
constricting the inlets of the left common carotid artery and the
left subclavian artery.
FIG. 10 depicts an occlusion catheter suitable for introduction
through the right subclavian artery.
FIG. 11 depicts an occlusion catheter capable of bridging between
the left common carotid artery and the left subclavian artery.
FIG. 11A depicts an aortic constriction catheter capable of causing
flow reversal down the left CCA.
FIG. 12 depicts incision sites on various peripheral arteries for
the insertion of the medical devices.
DETAILED DESCRIPTION
The cerebral circulation is regulated in such a way that a constant
total cerebral blood flow (CBF) is generally maintained under
varying conditions. For example, a reduction in flow to one part of
the brain, such as in stroke, may be compensated by an increase in
flow to another part, so that CBF to any one region of the brain
remains unchanged. More importantly, when one part of the brain
becomes ischemic due to a vascular occlusion, the brain compensates
by increasing blood flow to the ischemic area through its
collateral circulation via the Circle of Willis.
FIG. 1 depicts a normal cerebral circulation and formation of
Circle of Willis. Aorta 100 gives rise to right brachiocephalic
trunk 82, left common carotid artery (CCA) 80, and left subclavian
artery 84. The brachiocephalic artery further branches into right
common carotid artery 85 and right subclavian artery 83. The left
CCA gives rise to left internal carotid artery (ICA) 90 which
becomes left middle cerebral artery (MCA) 97 and left anterior
cerebral artery (ACA) 99. Anteriorly, the Circle of Willis is
formed by the internal carotid arteries, the anterior cerebral
arteries, and anterior communicating artery 91 which connects the
two ACAs. The right and left ICA also send right posterior
communicating artery 72 and left posterior communicating artery 95
to connect respectively with right posterior cerebral artery (PCA)
74 and left PCA 94. The two posterior communicating arteries and
PCAs, and the origin of the posterior cerebral from basilar artery
92 complete the circle posteriorly. The left CCA also gives rise to
external carotid artery (ECA) 78, which branches extensively to
supply most of the structures of the head except the brain and the
contents of the orbit. The ECA also helps supply structures in the
neck.
When occluding lesion 70 occurs acutely, for example, in left
internal carotid artery 90, as depicted in FIG. 2, blood flow in
the right cerebral arteries, left external carotid artery 78, right
vertebral artery 76, and left vertebral artery 77 increases,
resulting in a directional change of flow through the Circle of
Willis to compensate for the sudden decrease of blood flow in the
left internal carotid artery. Specifically, blood flow reverses in
right posterior communicating artery 72, right PCA 74, and left
posterior communicating artery 95. Anterior communicating artery 91
opens, reversing flow in left ACA 99, and flow increases in the
left external carotid artery, reversing flow along left ophthalmic
artery 75, all of which contribute to flow in left ICA 90 distal to
the occluding lesion.
Balloon catheters for achieving flow reversal in carotid arteries
were described in Barbut, U.S. Pat. No. 6,146,370, incorporated
herein by reference in its entirety. FIG. 3A depicts one embodiment
of the device for preventing distal embolization during use of
carotid instrumentation. The device comprises catheter 1 and
balloon occluder 10. The catheter has lumen 5 communicating with a
proximal end and port 6 at a distal end. The lumen and port are
adapted for introduction of therapeutic or diagnostic instruments,
e.g., an atherectomy catheter, angioplasty catheter, and stent, to
a carotid artery. Balloon occluder 10, communicating with inflation
lumen 11, is mounted on the distal end of the catheter proximal to
port 6. Manometer 15 is mounted distal to occluder 10 for
monitoring blood pressure downstream the occluder.
FIG. 3B depicts another embodiment of the device having
constricting member 20 mounted on a distal region of the catheter
proximal to port 6. Constricting member 20 communicates with
inflation lumen 21. The constrictor has central opening 22 that
allows passage of blood. Manometer 15 is mounted distal to
constrictor 20 for monitoring blood pressure downstream the
constrictor.
FIG. 4A depicts another embodiment of the device comprising
catheter 1, balloon occluder 10, and constrictor 20. Lumen 5 of the
catheter communicates with port 6 at distal end 7. The lumen and
port are adapted for introduction of therapeutic or diagnostic
instruments. Balloon occluder 10, communicating with inflation
lumen 11, is mounted on the distal end of the catheter proximal to
port 6. Balloon constrictor 20, communicating with inflation lumen
21, is mounted distal to port 6 and first occluder 10. The
constrictor has central opening 22 that allows passage of blood.
Inflation lumen 21 is an elongate member which, in certain
embodiments, is slidably inserted through catheter 1, and is
moveable longitudinally relative to catheter 1 and occluder 10.
FIG. 4B depicts another embodiment of the device having two
manometers. Manometer 15 is mounted distal to occluder 10 for
measuring blood pressure between the occluder and the constrictor.
Manometer 25 is mounted distal to constrictor 20 for measuring
blood pressure downstream from constrictor 20. Any of the
manometers of any device described herein will be understood to
include a tube communicating with a pressure gauge at the proximal
end of the catheter.
In FIG. 5, proximal ends 14 and 24 of respective manometers 15 and
25 are connected to pressure monitor 16 for measuring blood
pressure proximal and distal the constrictor. Inflation ports 13
and 23 communicate, respectively, with inflation lumens 11 and 21
for expanding balloon occluder 10 and constrictor 20. Lumen 5 of
the catheter communicates with proximal end 2, which includes
hemostatic valve 19.
FIGS. 5A, 5B, 5C, and 5D depict alternative devices for use in the
inventions described herein. Each catheter has first balloon 10 and
second balloon 20. All combinations of constrictors and occluders
are contemplated. Thus, first balloon 10 may be an occluder, and
second balloon 20 may be a constrictor (FIG. 5A). Alternatively,
first balloon 10 may be a constrictor, and second balloon 20 may be
a constrictor (FIG. 5B). Alternatively, first balloon 10 may be a
constrictor, and second balloon 20 may be an occluder (FIG. 5C).
Alternatively, first balloon 10 may be an occluder, and second
balloon 20 may be an occluder (FIG. 5D).
In using the device of FIG. 3A to treat an occluding lesion in the
right internal carotid artery, for example, a percutaneous incision
is first made on a peripheral artery, such as the femoral artery. A
guidewire is inserted. through the incision into the right
brachiocephalic artery in an antegrade direction. Alternatively,
the guidewire is inserted into the right brachiocephalic artery
from an incision in the left subclavian artery or left brachial
artery in a retrograde direction, or in a retrograde direction
through the right subclavian artery. The distal end of the catheter
is inserted over the guidewire, so that occluder 10 is positioned
in right brachiocephalic artery 82 as shown in FIG. 6A; where
needed, a guiding catheter can also be used. The guidewire is then
removed from the catheter.
Occluder 10 is slowly expanded to constrict right brachiocephalic
artery 82, causing progressive decline in right brachiocephalic and
CCA pressure as shown in FIG. 6B. The pressure in right
brachiocephalic artery 82 distal to occluder 10 can be measured by
manometer 15. At a critically low pressure in the brachiocephalic
artery, blood flow in right ICA 86 and CCA 85 reverses down toward
the brachiocephalic artery and into right subclavian artery 83. The
reversal of blood flow down the CCA and up the subclavian artery
can be verified fluoroscopically with dye.
After blood reversal is established from the CCA to the subclavian
artery, the devices and methods described above can be used in any
carotid procedures. For example, in FIG. 6C, interventional
catheter 30 carrying angioplasty balloon 31 is introduced through
lumen 5 and port 6 of the device. The angioplasty balloon is shown
expanding over atheromatous lesion 70 in right ICA 86, thereby
compressing the lesion and enlarging the lumenal diameter.
Compression of the atheroma by the angioplasty balloon often
generates embolic debris, including calcium, atheromatous plaque,
and thrombi. With reversal of blood flow from the ICA to the CCA
and into the right subclavian artery, distal embolization to the
intracranial cerebral arteries is avoided, thereby minimizing risk
of ischemic stroke. Distal embolization of the branches of the
subclavian artery has far less devastating consequences than the
ICA. Blood flow through the affected subclavian artery and its
branches is reduced but not abolished due to collateral
circulation. For example, collateral flow is established from right
vertebral artery 203 into right subclavian artery 83, and this flow
reversal in the vertebral artery protects against infarction in the
posterior circulation, including the brain stem. In the event that
flow reversal does not occur in the vertebral artery upon
brachiocephalic occlusion, second balloon 204 (see FIG. 6D) is
positioned within the takeoff to the vertebral artery to protect
against infarction in the posterior circulation.
In using the device of FIG. 3B to treat an occluding lesion in the
right common carotid artery, for example, the distal end of the
device is first inserted into right brachiocephalic artery 82 as
shown in FIG. 7A. Constricting member 22 is then expanded to
constrict the lumen of the brachiocephalic artery, causing reversal
of blood flow from right CCA 85 toward brachiocephalic artery 82
and into right subclavian artery 83 as shown in FIG. 7B. After
reversal of blood flow is verified angiographically, a therapeutic
instrument, such as an atherectomy catheter as depicted in FIG. 7C,
is inserted through lumen 5 and port 6 to treat the occluding
lesion. Embolic debris generated during the procedure is diverted
from CCA 85 toward subclavian artery 83, thereby preventing distal
cerebral embolization and ischemic stroke. The construction of
atherectomy catheters is well known in the art and will not be
repeated in detail here. The reader is referred instead to
Fischell, U.S. Pat. No. 5,409,454; Fischell, U.S. Pat. No.
4,898,575; Rydell, U.S. Pat. No. 4,857,045; Yock, U.S. Pat. Nos.
4,794,931, 5,000,185, and 5,313,949; Jang et al., U.S. Pat. No.
5,507,292; Farr, U.S. Pat. Nos. 4,950,277, 4,986,807, 5,019,088;
Shiber, U.S. Pat. Nos. 4,894,051, 4,957,482, 4,979,939, 5,007,896,
5,024,651, 5,135,531; Summers, U.S. Pat. No. 5,087,265; Plassche et
al., U.S. Pat. No. 5,318,576; Belknap, U.S. Pat. No. 5,366,464;
Jang et al., U.S. Pat. No. 5,402,790; Mazur et al., Catherization
and Cardiovascular Diagnosis 31:79-84 (1994); Fischell et al., U.S.
Pat. Nos. 4,886,061, 5,100,425; and Barbut et al., U.S. Pat. No.
5,662,671, all of which are incorporated herein by reference as if
fully set forth herein. In other embodiments, catheter 35 may carry
angioplasty balloon 36 or a stent.
If flow reversal does not occur due to insufficient blood flow from
contralateral circulation to the CCA, i.e., an insufficient
pressure gradient between the CCA and the subclavian artery, the
device of FIG. 5 is useful to increase the pressure gradient
between the CCA and the subclavian artery as shown in FIG. 8. In
use, the distal end of the device is inserted into right
brachiocephalic artery 82. The separation between occluder 10 and
constrictor 20 is adjusted to ensure proper placement in the
respective arteries. Preferably, occluder 10 is slowly expanded
through inflation lumen 11 to constrict brachiocephalic artery 82,
causing progressive decline of pressure in the subclavian artery.
The pressure in the subclavian artery distal to the constrictor and
the pressure in the subclavian artery distal to the occluder can be
measured, respectively, by manometers 25 and 15. At a critically
low pressure in the distal brachiocephalic artery, blood flow in
CCA 85 reverses toward the brachiocephalic artery and into the
subclavian artery. The reversal of blood flow down the CCA and up
the subclavian artery can be verified fluoroscopically with dye. If
flow reversal does not occur due to insufficient pressure gradient
between the CCA and the subclavian artery, constrictor 20 is
gradually expanded to further reduce the pressure in the subclavian
artery to create a more favorable pressure gradient between the CCA
and the subclavian artery to reverse blood flow into the subclavian
artery.
In treating an occluding lesion in the left common carotid artery,
the device of FIG. 3B is shown inserted in the inlets of left CCA
80 and left subclavian artery 84 as depicted in FIG. 9. Occluding
member 10 is expanded to limit blood flow from the aorta into the
CCA and the subclavian artery. After blood flow reverses from left
CCA 80 and into left subclavian artery 84, a therapeutic
instrument, such as a stent is inserted through lumen 5 and port 6.
The stent is shown deployed over the atheromatous lesion in CCA 80,
thereby compressing the lesion and enlarging the lumenal diameter.
With reversal of blood flow from the CCA to the subclavian artery,
distal embolization of debris generated by compression of the
atheromatous lesion to the intracranial cerebral arteries is
avoided, thereby minimizing risk of ischemic stroke.
FIG. 11 depicts an alternative embodiment wherein first and second
occluding members 10 are expanded to occlude each of the left CCA
and left subclavian artery. Flow reversal from left CCA 80 to left
subclavian 84 is established through tubular member 202 mounted at
the distal end of catheter 1. Interventional catheter is deployed
through tubular member 202 into left CCA 80. In certain
embodiments, a third balloon (not shown) will be used to block the
flow of emboli into the left vertebral artery. Flow reversal from
left CCA 80 to left subclavian 84 can also be accomplished by
placing constricting member 10 in the aorta between the
brachiocephalic artery and the left CCA as shown in FIG. 11A.
FIG. 10 depicts the use of a catheter adapted for retrograde
insertion into the right subclavian artery. Occlusion member 10 is
expanded in the right brachiocephalic artery to establish flow
reversal from the right CCA to the right subclavian. Catheter 30,
here an angioplasty catheter, is advanced through port 201 to
access stenosis 70 in right ICA 86.
FIG. 12 depicts different sites of entry for the devices disclosed
herein. An incision can be made on a peripheral artery, such as
right femoral artery 122, left femoral artery 120, right brachial
artery 112, left brachial artery 110, right axillary artery 126,
left axillary artery 115, right subclavian artery 142, or left
subclavian artery 140.
The length of catheter will generally be between 10 and 200
centimeters, preferably approximately between 30 and 150
centimeters. The inner diameter of the catheter lumen will
generally be between 0.2 and 0.8 centimeters, preferably
approximately between 0.3 and 0.5 centimeters. The diameter of the
expanded occluder will generally be between 0.3 and 2 centimeters,
preferably approximately 0.5 and 1.0 centimeters. The foregoing
ranges are set forth solely for the purpose of illustrating typical
device dimensions. The actual dimensions of a device constructed
according to the principles of the present invention may obviously
vary outside of the listed ranges without departing from those
basic principles.
Although the foregoing invention has, for the purposes of clarity
and understanding, been described in some detail by way of
illustration and example, it will be obvious that certain changes
and modifications may be practiced which will still fall within the
scope of the appended claims. For example, the devices and features
depicted in any depicted embodiment can be used in any other
depicted embodiment.
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